always pin

Author: Alex Peck

BitFaster.Caching/Lfu/CmSketchCore.cs

@@ -1,12 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Reflection;
 using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-
-
-
 
 #if !NETSTANDARD2_0
 using System.Runtime.Intrinsics;
@@ -37,7 +32,9 @@ public unsafe class CmSketchCore<T, I>
         private const long OneMask = 0x1111111111111111L;
 
         private long[] table;
+#if NET6_0_OR_GREATER
         private long* tableAddr;
+#endif
         private int sampleSize;
         private int blockMask;
         private int size;
@@ -117,13 +114,7 @@ public void Increment(T value)
         /// </summary>
         public void Clear()
         {
-            #if NET6_0_OR_GREATER
-            table = GC.AllocateArray<long>(table.Length, true);
-            long pointer = (long)Unsafe.AsPointer(ref table[0]);
-            tableAddr = (long*)pointer + pointer % 32;
-            #else
-            table = new long[table.Length];
-            #endif
+            Array.Clear(table, 0, table.Length);
             size = 0;
         }
 
@@ -132,15 +123,17 @@ private void EnsureCapacity(long maximumSize)
         {
             int maximum = (int)Math.Min(maximumSize, int.MaxValue >> 1);
 
-            #if NET6_0_OR_GREATER
-            // over alloc by 4 to give 32 byte buffer
-            table = GC.AllocateArray<long>(Math.Max(BitOps.CeilingPowerOfTwo(maximum), 8) + 4, true);
+#if NET6_0_OR_GREATER
+            // over alloc by 4 to give 32 bytes padding, tableAddr is then aligned to 32 bytes
+            const int buffer = 4;
+            table = GC.AllocateArray<long>(Math.Max(BitOps.CeilingPowerOfTwo(maximum), 8) + buffer, true);
             long pointer = (long)Unsafe.AsPointer(ref table[0]);
             tableAddr = (long*)pointer + pointer % 32;
-            #else
+            blockMask = (int)((uint)(table.Length-buffer) >> 3) - 1;
+#else
             table = new long[Math.Max(BitOps.CeilingPowerOfTwo(maximum), 8)];
-            #endif
-            blockMask = (int)((uint)(table.Length-4) >> 3) - 1;
+            blockMask = (int)((uint)(table.Length) >> 3) - 1;
+#endif
             sampleSize = (maximumSize == 0) ? 10 : (10 * maximum);
 
             size = 0;
@@ -265,7 +258,11 @@ private unsafe int EstimateFrequencyAvx(T value)
             Vector128<int> blockOffset = Avx2.Add(Vector128.Create(block), offset); // i - table index
             blockOffset = Avx2.Add(blockOffset, Vector128.Create(0, 2, 4, 6)); // + (i << 1)
 
+            #if NET6_0_OR_GREATER
             long* tablePtr = tableAddr;
+            #else
+            fixed (long* tablePtr = table)
+            #endif
             {
                 Vector256<long> tableVector = Avx2.GatherVector256(tablePtr, blockOffset, 8);
                 index = Avx2.ShiftLeftLogical(index, 2);
@@ -283,7 +280,7 @@ private unsafe int EstimateFrequencyAvx(T value)
                     .AsUInt16();
 
                 // set the zeroed high parts of the long value to ushort.Max
-#if NET6_0
+#if NET6_0_OR_GREATER
                 count = Avx2.Blend(count, Vector128<ushort>.AllBitsSet, 0b10101010);
 #else
                 count = Avx2.Blend(count, Vector128.Create(ushort.MaxValue), 0b10101010);
@@ -308,8 +305,11 @@ private unsafe void IncrementAvx(T value)
             Vector128<int> blockOffset = Avx2.Add(Vector128.Create(block), offset); // i - table index
             blockOffset = Avx2.Add(blockOffset, Vector128.Create(0, 2, 4, 6)); // + (i << 1)
 
-            //fixed (long* tablePtr = table)
-                long* tablePtr = tableAddr;
+            #if NET6_0_OR_GREATER
+            long* tablePtr = tableAddr;
+            #else
+            fixed (long* tablePtr = table)
+            #endif
             {
                 Vector256<long> tableVector = Avx2.GatherVector256(tablePtr, blockOffset, 8);